Bi language website based on Orchard CMS

i am trying to build new website based on orchard CMS but i need it to be bi language [Arabic - English ] where is the arabic language is the main language for the website, i checked and found that localization module is already installed on the orchard,
but i don't know how can i do it

You can find the Arabic language package here:
http://orchardproject.net/localization. Simply unzip its contents and copy the contents of its
Source folder to the root of your site's installation. This will copy all of the PO files to their proper locations.